Explosive composition



Patented July 21, 1936 UNITED STATES EXPLOSIVE COMPOSITION Samuel G. Baker, Jr., Wilmington, Del., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware N0 Drawing.

Application April 6, 1934,

Serial No. 719,299

22 Claims.

This invention relates to improved solid granular explosive compositions containing a watersoluble ingredient, more particularly non-gelatinous dynamite compositions containing ammonium nitrate, and to a process for rendering such compositions water resistant.

Various types of explosives in commercial use are adversely afiected by the presence of water at the place of use, because of their content of water-soluble ingredients. In many cases this adverse effect is sufilcient to make the explosives incapable of detonation in wet holes, while in other cases the explosives are rendered less effective and less dependable.

Among the explosives which are unsatisfactory under wet conditions are black powder, chlorate powders and the non-gelatinous dynamites. The latter class of explosives includes the straight dynamites and the so-called ammonia dynamites. The straight dynamites are non-gelatinous dynamites in which nitroglycerin is the sole explosive ingredient, the remainder of the composition consisting of oxidizing agents other than ammonium nitrate, carbonaceous absorbents for the nitroglycerin, acid-accepting materials, and many others. The term ammonia dynamite, on the other hand, is applied to those explosives in which ammonium nitrate is used in varying amounts to replace a portion of the nitroglycerin as the explosive ingredient. The straight dynamites are graded in strength according to their content of nitroglycerin, a 40% straight dynamite, for example, containing 40% of nitroglycerin. Similarly the ammonia dynamites are graded for strength, except that here this is given by reference to the straight dynamites. In addition to the graded ammonia dynamites, the ammonia permissibles may be considered in this class also, the ammonium nitrate content in this class being as high as 80% in some cases.

Neither the straight nor the ammonia dynamites are adapted for use in very wet work, as in general they do not possess high water resistance. Practically the only exception to this is in the case of the high strength straight dynamites, 60% straight for example, where the high nitroglycerin content and the low content of soluble salts are sufficient to allow their use, even in contact with water. The presence of the soluble sodium nitrate in the lower strength straight dynamites, and of the even more soluble ammonium nitrate in the ammonia dynamites, makes it impossible to use these explosives under such wet conditions.

The ammonia dynamites have given the most concern in this respect because of the deleterious effect of water and of atmospheric moisture on the extremely soluble and hygroscopic ammonium nitrate, and various methods have been suggested for overcoming this disadvantage. The dyna- 5 mite cartridges have been made substantially waterproof, for example, by enclosing in a waxed paper wrapper, the whole cartridge then being redipped in molten paramn, so that a solid impervious coating results on the cooling of the 10 paraflin. In loading such explosives into boreholes, however, it is customary to slit the cartridges before tamping, and the protecting coating is thus made useless. Another common method has been to coat the individual grains of 15 ammonium nitrate with paramn, or other low melting organic material not afiected by water. Not much success has been obtained by this means, however, since the complete covering of the ammonium nitrate particles requires the use 20 of an undesirably large amount of paramn or petrolatum, sufficient to have a decidedly adverse effect on the sensitiveness of the explosive as well as on the oxygen balance.

An object of my invention is an explosive com- 5 position, the water resistance of which has been substantially improved. A further object is such a composition in which the increased water resistance is brought about by the presence of a solid ingredient of a class not used heretofore for this purpose, preferably as a coating on the water-soluble salt contained in the explosive.

A still further object is the process for obtainin the improved water resistance. Other objects will be apparent as the invention is described hereinafter.

I have found that the foregoing objects are accomplished if a solid materal substantially insoluble in water, comprising a metallic salt of a higher aliphatic acid in finely divided condition, is included as an ingredient in the explosive. Various compounds are adapted for use according to my invention and I find preferable the insoluble metallic salts of the acids of the group consisting of stearic, palmitic, and oleic acids. As such desirable compounds I may employ calcium palmitate, ferric oleate, lead oleate and various insoluble stearates, for example the stearates of barium, calcium, magnesium, and aluminum. I find the stearates particularly desirable as waterproofing compounds, and my preferred waterproofing ingredient is calcium stearate.

My invention is applicable in the case of all solid granular explosive compositions containing a water-soluble salt that would be affected by the action of water under the conditions of blasting. It may be applied in the case of black powder 7 I compositions, for example, since these explosives possess very slight water resistance because of the preponderance of sodium nitrate or other soluble nitrate, usually between 70 and 75% of the total composition. I

Another field of use is in the case of chlorate explosives, where the very soluble sodium chlorate is the characteristic ingredient. Similarly, the method of waterproofing can be desirably applied to perchlorate explosives, in which ammonium, sodium or potassium perchlorate may be present.

I find the most desirable place for utilizing my invention, however, to be in the case of nongelatinous dynamites containing a water-soluble nitrate. Calcium stearate or other insoluble metallic salt of the higher aliphatic acids may be used with advantage, for example, in the straight dynamite compositions, particularly for the low strength straights where the nitroglycerlne content is low and a considerable amount of sodium nitrate is present. It is the ammonia dynamites, however, that have the greatest need of improved water resistance, and it is here that my invention is'most beneficial. While a waterproofing effect is imparted when the calcium stearate or other protecting compound is merely incorporated 'with the other ingredients by'mixingthe greatest improvement is obtained when the ammonium nitrate, or other water-soluble inorganic oxidizing salt, is first mixed withthe waterproofing compound, bringing about an improved coating on the ammonium nitrate.

My waterproofing method may likewise be utilized in the case of explosives based on ammonium nitrate, ammonium perchlorate or other inorganic explosive salts, wherea sensitizing agent is used with the explosive salt. Such sensitizer in the case of the ammonia dynamites discussed in the preceding paragraph was nitroglycerin, but it may be other nitric esters, for example. nitrostarch, pentaerythritol tetranitrate and the like. Other sensltizers, however, maybe used, such as trinitrotoluene or other aromatic nitrocompound, metallic sensitizers such as finely divided aluminum, magnesium, ferrosilicon, calcium silicide, and similar materials.

As illustrative of the benefits resulting from my invention, I may cite the following compositions in which (1) represents an ammonia dynamite containing no waterproofing ingredient, while (2) shows a similar composition containing calcium stearate.

The effect of the waterproofing ingredient in the foregoing formulas is very apparent. The water resistance given represents the time in hours, during which the various dynamites were exposed to the action of water and at theend of which no failures to detonate were obtained in tion and in the subsequent claims, I have desig nated compounds of higher aliphatic acids as desirable. -While this term will be readily understood, I wish it to be interpreted as comprising long-chain aliphatic acids containing at least ".12 carbon atoms, such acids to be of either the saturated or the unsaturated series. My invention has been described in detail in Y the foregoing, but it will be apparent that many variations may be made in the exact'compositions used. For example, in place of nitroglycerin, other liquid explosive nitric esters may be used, such asethylene glycol dinitrate, nitrochlorhydrins and the like, as well as nitroglycerin con taining in solution various freezing point depressants. It will be understood that the in;

soluble metallic salts of the higher aliphatic acids maybe designated also as insoluble soaps.

Having described my invention fully, I intend to be limited only by the following patent claims.

I claim: v

1. A solid granular explosive composition containing a water-soluble inorganic oxidizing salt and a sufficient quantity of an ingredient imparting water resistance properties to the composition but insufiicient in quantity to affect the strength of the explosive comprising a metallic salt of a higher aliphatic acid, said salt being substantially insoluble in water.

v2. A solid non-gelatinous explosive composition containing a water-soluble inorganic oxidizing salt and a sufiicient quantity of an ingredient imparting water resistance properties to the composition but insufficient in quantity to affect the strength of the explosive comprising a, metallic salt of a higher aliphatic acid taken from a group consisting of stearic, palmitic, and oleic acids, said salt being substantially insoluble in water.

3. The composition of claim 1, in which the substantially insoluble metallic salt is calcium stearate.

4. A modified black powder composition comprising a water-soluble inorganic nitrate and a suflicient quantity of an ingredient imparting water resistance properties to the composition but insufficient in quantity to aiiect the strength of the explosive comprising a metallic salt of a higher aliphatic acid, said salt being substantially insoluble in water.

5. A modified black powder composition comprising a water-soluble inorganic nitrate, sulfur, charcoal, and a quantity of calcium stearate sufilcient to produce a water-proofing effect, but insufiicient in quantity to affect the strength of the powder.

6. An explosive composition comprising a. water-soluble inorganic chlorate and a sufficient quantity of an ingredient imparting water resistance properties to the composition but insufllcient in quantity to afiect the strength of the explosive comprising a metallic salt of a higher aliphatic acid, said salt being substantially insoluble in water.

7. An explosive composition comprising sodium chlorate and a suflicient amount of calcium stearate to impart water resistance properties to the composition but insuflicient to affect the strength of the explosive.

8. An explosive composition comprising an explosive nitric ester, a water soluble inorganic oxidizing salt, and a sufficient quantity of an ingredient imparting water resistance properties to the composition but insuflicient in quantity to aflect the strength of the explosive comprising a metallic salt of a higher aliphatic acid, said salt being substantially insoluble in water.

9. An explosive composition comprising an inorganic explosive oxidizing salt, a sensitizing agent therefor, and a suflicient quantity of an ingredient imparting water resistance properties to the composition but insufficient in quantity to affect the strength of the explosive comprising a metallic salt of a higher aliphatic acid, said salt being substantially insoluble in water.

10. An explosive composition comprising ammonium nitrate, a sensitizing agent therefor, and a suflicient quantity of an ingredient imparting water resistance properties to the composition but insuflicient in quantity to aifect the strength oi the explosive comprising a metallic salt of a higher aliphatic acid, said salt being substantially insoluble in water.

11. An explosive composition comprising ammonium nitrate, an explosive nitric ester as sensitizing agent therefor, and an ingredient imparting water resistance properties to the composition but insufiicient in quantity to afiect the strength of the explosive comprising a metallic salt of a higher aliphatic acid, said salt being substantialiy insoluble in water.

12. A dynamite composition comprising a liquid explosive nitric ester, a water-soluble inorganic oxidizing salt, and an ingredient imparting water resistance properties to the composition but insufliclent in quantity to aflect the strength of the explosive comprising a metallic salt of a higher aliphatic acid, said salt being substantially insoluble in water.

13. A dynamite composition comprising a liquid explosive nitric ester, and a sufilcient quantity of a water-soluble inorganic oxidizing salt, said salt having a water-protecting coating of a metallic salt of a higher aliphatic acid insuflicient in amount to aflect the strength of the explosive, said metallic salt being substantially insoluble in water.

14. A dynamite composition comprising a liquid explosive nitric ester, ammonium nitrate, and a sufficient quantity of an ingredient imparting water resistance properties to the composition but insuflicient in quantity to afiect the strength of the explosive comprising a metallic salt of a higher aliphatic acid taken from a group consisting of stearic, palmitic, and oleic acids, said salt being substantially insoluble in water.

15. The composition of claim 14, in which the metallic salt is barium stearate.

16. The composition of claim 14, in which the metallic salt is magnesium stearate.

17. The composition of claim 14, in which the a quantity of calcium stearate sufiicient to produce a water-proofing effect, but insuflicient in quantity to afiect the strength of the powder.

20. The composition of claim 19, in which the calcium stearate is present as a coating on the ammonium nitrate in the amount of 0.1 to 2.0% by weight of the total composition.

21. The process of waterproofing a non-gelatinous dynamite composition containing ammonium nitrate which process comprises coating said ammonium nitrate with a quantity of calcium stearate sufficient to produce a waterproofing efiect, but insufficient in quantity to affect the strength of the powder, and subsequently incorporating the coated nitrate with the other dynamite ingredients.

22. The process of rendering waterproof a solid granular explosive composition containing a water-soluble oxidizing salt, which process comprises treating said water-soluble salt with a metallic salt of a higher aliphatic acid, said latter salt being substantially insoluble in water and being added in an amount sufflcient to produce a waterproofing efieot but insuflicient to afiect substantially the strength of the explosive, and incorporating said treated water-soluble salt with the other ingredients.

. SAMUEL G. BAKER, JR. 

